I used this information to successfully create a "crossover" cable to connect two reface's with one cable (this cable send the MIDI OUT of each Reface to the MIDI IN of the other).
Orient the cable so that you are looking at the 6 pins (mini-DIN male end), with the little arrowhead at 12 o'clock. This is the orientation in which you can plug the cable into the reface. Starting at 12 o'clock (where there is no pin) and going clockwise, the pins are numbers as follows: 6, 4, 2, 1, 3, 5.
Pins 6, 4, and 2 (the 3 on on your right) are MIDI OUT
Pins 1, 3, and 5 (the 3 on your left) are MIDI IN
The specific connections are as follows:
Pin 1: MIDI IN, Ground via decoupling capacitor
Pin 2: MIDI OUT, Ground
Pin 3: MIDI IN, LED cathode (-)
Pin 4: MIDI OUT, TX serial data
Pin 5: MIDI IN, LED anode (+)
Pin 6: MIDI OUT, pull-up to 3.3V
To make my crossover cable, I bought a kenable 6-pin audio video cable, cut it in half, and reconnected the wires so that the pins on one end were connected to the pins on the other end as follows:
Pin 6 to Pin 5
Pin 4 to Pin 3
Pin 2 to Pin 1
Pin 1 to Pin 2
Pin 3 to Pin 4
Pin 5 to Pin 6
This replaces 4 cables (the 2 breakout cables, and the 2 standard MIDI cables that connect them to each other).